Air flotation of silica bearing oxidized copper ore



United States Patent O F AIR FLOTATION OF SILICA BEARING OXIDIZED COPPER ORE Nathaniel Arbiter, Sparkill, N. Y.

No Drawing. Application July 5, 1955 Serial No. 520,093

5 Claims. (Cl. 209-166) My invention relates to a method for the flotation concentration of oxidized copper ores which contain chrysocolla.

It is conventional in the art to concentrate certain copper-bearing ores by flotation. In such an operation, the run-of-mine ore is usually first crushed in large gyratory or jaw cnishers for the primary breaking, and thereafter in secondary crushers or rolls to produce finer sizes. Rod mills and ball mills are used for fine grinding. Generally it is necessary to grind the ores quite finely, usually sufliciently to pass a 40- or 60-mesh screen, in order to free a high percentage of the valuable mineral which is present in the ore. Following this, the ore in admixture with water and appropriate flotation reagents is subjected to a flotation operation in order to produce a flotation concentrate, which is thereafter dewatered,

' thickened and filtered to provide a concentrate which is suitable for smelting.

Prior to my present invention, the sulfide ores have been the most important ores of copper. Such ores are usually mixtures of copper and iron sulfides in admixture with compounds of various other metals. Methods have been well worked out in the art for the flotation of the Sulfide ores. Although there are large deposits of copper silicate ores containing chrysocolla, for example, in various parts of the world, means have not been available in the past for floating them satisfactorily, and it is therefore the primary object of my invention to provide the art with a satisfactory method for the flotation concentration of the oxidized copper ores which have the mineral chrysocolla present therein.

This object is accomplished in accordance with my invention by adding to the aqueous pulp before the flotation step is carried out a Water-soluble inorganic sulfide, a water-soluble salt of Z-mercaptobenzothiazole, and copper sulfate, the Water-soluble salt of Z-mercaptobenzothiazole serving as a collector.

EXAMPLE I As a specific illustration of an operation falling within the scope of my invention, a 500 gram sample of 6-mesh oxidized Chilean ore which was essentially a mixture of chrysocolla, quartz and minor amounts of magnetite, manganese oxides and clay was ground in three stages to provide a 385 gram fraction passing through a 65-mesh screen. This 385 gram fraction was mixed thoroughly with two liters of water, following which the mixture was permitted to settle for 5 minutes. The suspended material was removed by siphoning, leaving 285 grams of deslimed ore. 4

The deslimed ore, in admixture with two liters of water, was placed in a conventional laboratory flotation cell and 3.92 grams of CuSO .5H O was added. The mixture was then stirred for 5 minutes and unreacted copper sulfate was removed by decantation. Following this, water in suflicient amount was added to bring the volume of the mixture back to the volume which it had before the decantation, and 0.75 gram of the sodium 2,829,770 Patented Apr. 8, 1958 p ice salt of Z-mercaptobenzothiazole and 0.25 gram of Na S.9H O were added. The mixture. was agitated for 15 seconds without air, and air was then introduced and concentrate removed overhead for a period of 4 minutes. This rougher concentrate was then subjected to a second flotation in a duplicate of the first cell, sufficient water having been added to the rougher concentrate so that the volume of the flotation mixture was the same as it was during the first flotation operation. No additional reagents were added.

Table I below sets forth the results obtained when this procedure was carried out. It will be noted that the cleaner concentrate produced as an overhead in the second flotation step contained 16.3 percent by weight of copper and 88.7 percent of the copper present in the original flotation feed.

This experiment was conducted using the procedure of Example I, the only difference being that in the desliming operation sodium silicate was also used in the amount of 5 pounds per ton of ore. The results of this experiment are set forth in Table II below.

Table II Copper Copper Copper, Wt., Distrib., Distrib., Product Percent Percent Percent of Percent of Total Flotation Feed Feed Head (calc.) 3. 68 100.0 0.49 9.9 81 3. 40 12.8 Flot. Feed 4. 20 77.3 Cleaner Gone 15. 83 15.6 I Cleaner Tail.-. 7.17 7. 2 Rougher Tail 0. 42 54. 5

Various modifications can be made in the teachings of the specific examples to provide other embodiments which fall within the scope of my invention for the air flotation concentration of oxidized copper-bearing ores containing chrysocolla. Thus, in place of the CuSO .5H O employed in the specific examples, there can be substituted an equimolar amount of CuSO or mixtures of the two copper sulfates can be used. Furthermore, although in the specific examples unreacted copper sulfate was removed by decantation before the actual flotation was begun, this step is not essential to my invention. Thus, if desired, the excess copper sulfate need not be removed, although it preferably is in order that it can be used again in the treatment of further batches of copper-containing ore. In general, the copper sulfate, either anhydrous or hydrated, will be used in amount such that from about 2 to 15 parts by Weight of copper present in the copper sulfate will be added per parts by weight of copper present in the ore.

In the specific example, Na S.9H O was added to the pulp before the flotation was begun. In place of this there can be substituted other inorganic, water-soluble sulfides, vsuch as Na S, H 8, K 5 K S.5H O, calcium polysulfide or mixtures of the inorganic water-soluble sulfides. The amount added will be such that from about 0.1 to 1.0 grams of sulfur present in the inorganic water-soluble sulfide is introduced per .100 grams of copperpresent'in the ore. Also, in place of the sdium salt of Z-mercaptobenzothiazole there can be substituted other inorganic Water-soluble salts of Z-mercaptobenzothiazole, such as the potassium or ammonium salt or mixtures thereof. The amount of Water-soluble salt of Z-mercaptobenzothiazole introduced into the flotation mixture will generally be from about 1 to 10 grams per 100 grams of copper present in the ore.

I claim:

1. In the air flotation of oxidizedvcopper ore containing chrysocolla, the step of adding to the aqueous pulp before flotation a water-soluble inorganic sulfide, a watersoluble salt of. 2- mercaptobenzothiazole, and copper sulfate.

2. The method of claim 1 wherein the water-soluble inorganic sulfide is sodium sulfide.

3. The method of claim 1 wherein the water-soluble salt of Z-mercaptobenzothiazole is the sodium salt.

4. The method of claim 1 wherein the sulfur present in the water-soluble inorganic sulfide is within the range from 0.1' to 1 gram per 100 grams of copper present in the ore, wherein the amount of water-soluble salt of 2- mercaptobenzothiazole added is within the range from 1 to 10 grams per 100 grams of copper present in the ore and wherein the copper present in the copper sulfate is within the range from 2 to 15 grams per 100 grams of copper present in the ore. 7

5. The method of claim -4 wherein the water-soluble inorganic sulfide is sodium sulfide and wherein the watersoluble salt of Z-mercaptobenzothiazole is the sodium salt.

OTHER REFERENCES Taggart: Handbook of .Mineral Dressing, c. .1945, pages 12-121. 

1. IN THE AIR FLOTATION OF OXIDIZED COPPER ORE CONTAIN ING CHRYSOCOLLA, THE STEP OF ADDING TO THE AQUEOUS PULP BEFORE FLOTATION A WATER-SOLUBLE INORGANIC SULFIDE, A WATERSOLUBLE SALT OF 2-MERCAPTOBENSOTHIAZOLE, AND COPPER SULFATE. 